import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.Scanner;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class TcpEchoServer {
    private ServerSocket serverSocket= null;

    public TcpEchoServer(int port) throws IOException {
        serverSocket = new ServerSocket(port);
    }

    public void start() throws IOException {
        System.out.println("启动服务器");
        //创还能线程池
        ExecutorService service = Executors.newCachedThreadPool();
        ExecutorService service1 = Executors.newFixedThreadPool(10);
        while(true) {
            //建立连接
            Socket clientSocket = serverSocket.accept();
            //创建线程，每个线程去服务一个客户端

            /*Thread t = new Thread(() -> {
                try {
                    processConnection(clientSocket);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            });
            t.start();*/
//
            
            //使用线程池，
            service.submit(() -> {
                try {
                    processConnection(clientSocket);
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            });
        }
    }

    //针对一个连接，提供处理逻辑
    private void processConnection(Socket clientSocket) throws IOException {
        //打印客户端信息
        System.out.printf("[%s:%d] 客户端上线！\n",clientSocket.getInetAddress(),clientSocket.getPort());
        try(InputStream inputStream = clientSocket.getInputStream();
            OutputStream outputStream = clientSocket.getOutputStream()){
            Scanner scanner = new Scanner(inputStream);
            PrintWriter printWriter = new PrintWriter(outputStream);
            //使用 Scanner 包装一下 InputStream，就可以更方便地读取这里的请求数据了
            while(true) {
                // 1. 读取请求并解析
                if(!scanner.hasNext()){
                    //如果 scanner 无法读取数据，说明客户端关闭了连接，导致服务器这边读取到 “末尾”
                    break;
                }
                String request = scanner.next();
                // 2. 根据请求计算响应
                String response = process(request);
                // 3. 把响应写回给客户端
                printWriter.println(response);
                printWriter.flush();

                System.out.printf("[%s:%d] req=%d; resp=%s\n", clientSocket.getInetAddress(),clientSocket.getPort());

            }
        }catch (IOException e){
            e.printStackTrace();
        }finally {
            //服务器结束循环，才能调用后续的 close
            System.out.printf("[%s:%d] 客户端下线！\n",clientSocket.getInetAddress(),clientSocket.getPort());
            clientSocket.close();
        }
    }

    private String process(String request) {
        return request;
    }

    public static void main(String[] args) throws IOException {
        TcpEchoServer server = new TcpEchoServer(9090);
        server.start();
    }
}
